The MS28778-4 is an aerospace-standard O-ring sealing element used in aircraft hydraulic, fuel, pneumatic, and lubrication systems. It provides a reliable leak-proof seal between mating surfaces such as fittings, valve bodies, pumps, and actuator housings.

This O-ring is designed to maintain sealing performance under high pressure, vibration, and wide temperature variations typical of aviation environments. It is commonly used in both static sealing applications and lightly dynamic interfaces depending on system requirements.

Manufactured to MS specifications, it is typically made from FKM (Viton-type) or equivalent aerospace-grade elastomer, offering strong resistance to aviation fuels, hydraulic fluids, oils, and environmental aging.

Key features include:

MS28778-4 aerospace O-ring seal
Used in hydraulic, fuel, and pneumatic systems
Provides reliable pressure-tight sealing
Resistant to aviation fluids and oils
High temperature and pressure capability
Suitable for vibration and cyclic loads
FKM (Viton-type) elastomer construction
Used in fittings, valves, pumps, and actuators
Standard MS aircraft sealing component
Direct replacement per MS aerospace hardware standards